GET /chat HTTP/1.1 
　　Host: server.example.com 
　　Upgrade: websocket //告诉服务器现在发送的是WebSocket协议
　　Connection: Upgrade 
　　Sec-WebSocket-Key: x3JJHMbDL1EzLkh9GBhXDw== //是一个Base64 encode的值，这个是浏览器随机生成的，用于验证服务器端返回数据是否是WebSocket助理
　　Sec-WebSocket-Protocol: chat, superchat 
　　Sec-WebSocket-Version: 13 
　　Origin: http://example.com

HTTP/1.1 101 Switching Protocols 
　 Upgrade: websocket //依然是固定的，告诉客户端即将升级的是Websocket协议，而不是mozillasocket，lurnarsocket或者shitsocket
　 Connection: Upgrade 
　 Sec-WebSocket-Accept: HSmrc0sMlYUkAGmm5OPpG2HaGWk= //这个则是经过服务器确认，并且加密过后的 Sec-WebSocket-Key,也就是client要求建立WebSocket验证的凭证
　 Sec-WebSocket-Protocol: chat

<?php

if(($socket = socket_create(AF_INET,SOCK_STREAM,SOL_TCP)) < 0) {
    echo "socket_create() 失败的原因是:".socket_strerror($sock)."\n";
}
if(($ret = socket_bind($socket,'127.0.0.1','9090')) < 0) {
    echo "socket_bind() 失败的原因是:".socket_strerror($ret)."\n";
}
if(($ret = socket_listen($socket,3)) < 0) {
    echo "socket_listen() 失败的原因是:".socket_strerror($ret)."\n";
}

$all_sockets = [$socket];    // socket 集合

do {
    $copy_sockets = $all_sockets;   // 单独拷贝一份

    // 因为客户端是长连接，如果客户端非正常断开，服务端会在 socket_accept 阻塞，现在使用 select 非阻塞模式 socket
    if(socket_select($copy_sockets, $write, $except, 0) === false)
        exit('sosket_select error!');

    // 接收第一次 socket 连入，连入后移除服务端 socket
    if(in_array($socket, $copy_sockets)) {
        $client = socket_accept($socket);
        if($client) {
            $buf = socket_read($client, 1024);
            echo $buf;

            // 匹配 Sec-Websocket-Key 标识
            if (preg_match("/Sec-WebSocket-Key: (.*)\r\n/i",$buf,$match)) {
                // 需要将 Sec-WebSocket-Key 值累加字符串，并依次进行 SHA-1 加密和 base64 加密
                $key = base64_encode(sha1($match[1] . '258EAFA5-E914-47DA-95CA-C5AB0DC85B11',true));
                // 拼凑响应内容
                $res= "HTTP/1.1 101 Switching Protocol".PHP_EOL
                    ."Upgrade: WebSocket".PHP_EOL
                    ."Connection: Upgrade".PHP_EOL
                    ."WebSocket-Location: ws://127.0.0.1:9090".PHP_EOL
                    ."Sec-WebSocket-Accept: " . $key .PHP_EOL.PHP_EOL;  // 注意这里，需要两个换行
                // 向客户端应答 Sec-WebSocket-Accept
                socket_write($client, $res, strlen($res));
                // 向客户端发送消息
                socket_write($client, buildMsg('socket ok'), 1024);

                // 加入客户端 socket
                $all_sockets[] = $client;
            }
            // 移除服务端 socket
            $key = array_search($socket, $copy_sockets);
            unset($copy_sockets[$key]);

            // socket_close($client);
        }
    }

    // 循环所有客户端 sockets
    foreach ($copy_sockets as $s) {
        // 获取客户端发给服务端的内容
        $buf = socket_read($s, 8024);
        echo strlen($buf).'---'.PHP_EOL;
        // 代表客户端主动关闭
        if(strlen($buf) < 9) {
            $key = array_search($s, $all_sockets);
            unset($all_sockets[$key]);
            socket_close($s);
            continue;
        }
        // 输出
        echo getMsg($buf).PHP_EOL;
    }

}while(true);
socket_close($socket);

// 编码服务端向客户端发送的内容
function buildMsg($msg) {
    $frame = [];
    $frame[0] = '81';
    $len = strlen($msg);
    if ($len < 126) {
        $frame[1] = $len < 16 ? '0' . dechex($len) : dechex($len);
    } else if ($len < 65025) {
        $s = dechex($len);
        $frame[1] = '7e' . str_repeat('0', 4 - strlen($s)) . $s;
    } else {
        $s = dechex($len);
        $frame[1] = '7f' . str_repeat('0', 16 - strlen($s)) . $s;
    }
    $data = '';
    $l = strlen($msg);
    for ($i = 0; $i < $l; $i++) {
        $data .= dechex(ord($msg{$i}));
    }
    $frame[2] = $data;
    $data = implode('', $frame);
    return pack("H*", $data);
}

// 解析客户端向服务端发送的内容
function getMsg($buffer) {
    $res = '';
    $len = ord($buffer[1]) & 127;
    if ($len === 126) {
        $masks = substr($buffer, 4, 4);
        $data = substr($buffer, 8);
    } else if ($len === 127) {
        $masks = substr($buffer, 10, 4);
        $data = substr($buffer, 14);
    } else {
        $masks = substr($buffer, 2, 4);
        $data = substr($buffer, 6);
    }
    for ($index = 0; $index < strlen($data); $index++) {
        $res .= $data[$index] ^ $masks[$index % 4];
    }
    return $res;
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        // 创建一个Socket实例
        var socket = new WebSocket('ws://localhost:9090');

        // 打开Socket
        socket.onopen = function(event) {
            // 发送一个初始化消息
            socket.send("init msg");

        };
        socket.onmessage = function(event) {
            console.log('收到消息',event);

        };

        // 监听Socket的关闭
        socket.onclose = function(event) {
            console.log('关闭监听',event);
        };

        function  send()
        {
            socket.send("client msg");
        }
    </script>
</head>
<body>
<button onclick="send()">发送消息</button>
</body>
</html>